Hi Bill,
In addition to what Hans stated, if you have the three flashes and the transmission stops, that could be an RF feedback problem.? Try transmitting into a dummy load using the terminal emulator, then using WSJT-X, and finally attaching the antenna.? If it works until you transmit with the antenna, you have RF feedback into the shack.? You can try snap-on ferrites on all the leads into and out of the QDX.? That has helped others, including myself, until you can adjust the antenna so there is no RF getting back down the transmission line.
73
Evan,
AC9TU
